Abstract: Elucidating patterns of marine population connectivity is a central concern among
biologists. Genetic markers are commonly utilized to quantify patterns of connectivity since
they can reveal information about the exchange of genes, and thus migration events. The
development of microsatellites as polymorphic, high resolution markers has significantly
contributed to our understanding of population genetic structure in marine organisms. In this
study, microsatellite loci were isolated from an enriched genomic library for the mutton snapper,
Lutjanus analis, a commercially and recreationally valuable fish. This species is of particular
interest to both conservationists and fishery managers, as the last known mutton snapper
spawning aggregation in United States’ waters was recently targeted for the establishment of the
Dry Tortugas Ecological Reserve (DTER). In order to evaluate the potential utility of the reserve
as a source population for fisheries of the southeastern United States, mutton snapper from five
locations around the Caribbean were genotyped at eight loci to estimate interpopulation gene
flow. Analyses ranging from population-based F-statistics to individual-based assignment
indicated that population genetic substructure was largely absent from the five sample locations.
The only evidence for structure identified the population from the west coast of Puerto Rico as
most distinct, suggesting that future work on populations in the eastern Caribbean is warranted.
The genetic similarity of mutton snapper populations implies free gene flow between
populations; however, because the genetic composition of each sample was so similar, it is
impossible to discern between the relative contributions of potential source populations. Thus
we cannot rule out the possibility that the DTER serves as a significant source of recruits to the
southeastern United States. Yet based on the results of this study we cannot confirm that is doe Further research will be required to properly evaluate the utility of the DTER and to clarify
corridors of connectivity across both the eastern and western portions of the Caribbean.